UPnP bug fix: When disabling UPnP from options dialog we get a hang.
UPnP bug fix: When disabling UPnP from options dialog we get a hang.

The UPnP thread is not getting a signal to shutdown when the UPnP
option is deselected from the options dialog, as a result the dialog
just hangs.  Here we just set a boolean when MapPort() is called which
then tells the UPnP thread to shutdown.

Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited